Carbendazim Case Study

2.4.4. Toxicokinetics of MT:
Both carbendazim and Methyl Thiophanate are classified as benzimidazole fungicides. Carbendazim is a major metabolite of benomyl with closely similar structural and toxicological characteristics. Methyl Thiophanate is also structurally related to both carbendazim and benomyl.
Both benomyl and carbendazim are well absorbed after oral exposure (80–85%) but poorly absorbed after dermal exposure (1 or 2%) in rats, mice, dogs and hamsters. The major pathway of clearance is urinary elimination in rats and mice, but in dogs the majority of the dose (83.4%) is eliminated via feces, with only 16.2% of the dose eliminated in the urine after 72 h of dosing. In animals, benomyl
7) is a dimethyl dithiocarbamate compound used as a fungicide to prevent crop damage in the field and to protect harvested crops from deterioration in storage or transport. Thiram is also used as a seed protectant and to protect fruit, vegetable, ornamental, and turf crops from a variety of fungal diseases. In addition, it is used as an animal repellent to protect fruit trees and ornamentals from damage by rabbits, rodents, and deer. Thiram is available as dust, flowable, wettable powder, water dispersible granules, and water suspension formulations, and in mixtures with other fungicides. Thiram has been used in the treatment of human scabies, as a sunscreen, and as a bactericide applied directly to the skin or incorporated into soap (EPA.,
Repeated or prolonged exposure to thiram can also cause allergic reactions such as dermatitis, watery eyes, sensitivity to light, and conjunctivitis (Edwards et al., 1991). Except for the occurrence of allergic reactions, harmful chronic effects from thiram have been observed in test animals only at very high doses. In one study, a dietary dose of 125 mg/kg/day thiram was fatal to all rats within 17 weeks. Oral doses of about 49 mg/kg/day to rats for 2 years produced weakness, muscle incoordination, and paralysis of the hind legs. Rats fed 52 to 67 mg/kg/day for 80 weeks exhibited hair loss, and paralysis and atrophy of the hind legs. Symptoms of muscle incoordination and paralysis from thiram poisoning have been shown to be associated with degeneration of nerves in the lower lumbar and pelvic regions. Day-old white leghorn chicks fed 30 and 60 ppm for 6 weeks exhibited bone malformations. At doses of about 10% of the LD50 for 15 days, thiram reduced blood platelet and white blood cell counts, suppressed blood formation, and slowed blood coagulation in rabbits (Edwards et al.,